The Effects of Accel and Carbaryl on Fruit Set and Fruit Quality of Three Apple Cultivars

Apple trees set more fruit than needed for a full crop. They will retain this heavy set of fruit throughout the growing season resulting in small, poorly coloured low quality fruit. It is important to thin apple fruit to achieve optimum fruit growth and enhance tree vigour. With a heavy crop 70-80% of the fruit may have to be removed. Chemical fruit thinning of apple (Malus pumila Mill) following bloom is a standard practice to improve fruit size, quality, increase return bloom and reduce biennial bearing (Williams, 1979; Looney, 1986). An apple tree with excessive fruit produces many small, low value fruit. In contrast a tree that is over thinned and only has few fruit does not produce to its maximum potential. Insufficient thinning may also lead to alternate bearing, whereby an extremely heavy crop is produced every year. Different factors affect success of thinning apples. Several chemicals such as Vydate, Sevin, NAA (1-napthaleneacetic acid) and Accel are used in different combinations to yield the best results.